Method and means for tuning musical instruments



y 1965 c. P. VAN OOYEN 3,183,761

METHOD AND MEANS FOR TUNING MUSICAL INSTRUMENTS Filed March 19, 1962INVENTOR. CLAW/2E I? 1/4/1/ 0055/1/ United States Patent 3,183,761METHOD AND MEANS FOR TUNING MUSICAL INSTRUMENTS Claude P. Van Ooyen,3710 Cheyenne Drive SW., Grandville, Mich. Filed Mar. 19, 1962, Ser. No.180,475 Claims. (Cl. 84-455) This invention relates to a novel method oftuning certain musical instruments, and to a device adapted to carry outthe method.

Certain musical instruments, such as pianos for example, produce musicaltones by causing a steel String to vibrate. The tension of the string isthe primary factor in determining the pitch of the sound produced.Tuning such instruments correctly has heretofore been an art requiringunusual skill and a highly trained ear. In large instruments such aspianos, tuning was a long and labori ous process even for such skilledtuners. As a general rule, it is customary for a tuner to tune the pianoagainst itself, i.e. the tuner takes one of the middle A strings of thepiano as a refernce and tunes all the other strings of the piano withrelation to that string. This is the usual method because temperaturechanges and similar factors affect the pitch of the strings but preservetheir frequency ratio, so that the piano still sounds properly tunedeven though its pitch is not exactly correct. If an exact pitch isdesired, however, the reference string may first be tuned correctly bytuning it against a tuning fork. The tuning itself is accomplished byaural comparison of an untuned string with a previously tuned string.Another string of the same pitch as the previously tuned string, or astring differing from it by an even octave, is tuned by the absence ofinterference beats. Fourth or fifths are tuned by observing thefrequency of the interference beats and adjusting them properly. Sincethe interference beats are too fast to permit accurate counting, thetraining of the tuners ear is a crucial factor in obtaining properadjustment. For the same reason, no two pianos are ever tuned exactlythe same way, because the tuning in last analysis is an approximation oran educated guess on the part of the tuner. Stroboscopic optical meanshave previously been used to eliminate this guesswork, but these opticaldevices have not found wide acceptance because in last analysis, aphysiologically pleasing sound rather than scientific precision is theultimate criterion in the tuning of musical instruments.

The present invention provides a simple, effective, and highly accuratemethod of tuning such instruments which requires little skill on thepart of the operator and permits rapid and accurate tuning of a largenumber of strings.

The present invention accomplishes this result by taking advantage ofthe magnetic properties of the steel strings used in the construction ofcertain musical instruments. The method of tuning in accordance withthis invention consists of creating an oscillating magnetic field ofpredetermined frequency in the immediate vicinity of the string to betuned. If the frequency of the magnetic oscillations is exactly equal tothe fundamental frequency of the string, or to a harmonic or subharmonicthereof, the string will resonate and emit an audible sound whose volumeand clarity are maximum when the fundamental frequency of the string andthe frequency of the magnetic field are precisely equal.

It is therefore the primary object of this invention to provide a novelmethod of tuning musical string instruments whose strings are made ofmagetizable material, by magnetically exciting the strings into resonantoscillations of a predetermined frequency.

It is a further object of this invention to provide a mechanism by whichmagnetic oscillations of exactly controllable frequency can be producedfor the purposes of this invention.

It is another object of this invention to provide a tuning probe whichpermits the magnetic excitation of a magnetizable string of a musicalinstrument without interference from adjacent strings of similar tonalcharacteristics.

These and other objects of the invention will become apparent from thefollowing specification, taken in connection with the accompanyingdrawings in which:

FIG. 1 is a schematic representation of the apparatus of this invention;

FIG. 2 is a side elevation of a commutator such as might be used incarrying out this invention;

FIG. 3 is a Vertical cross section of a tuning probe usable in carryingout this invention;

FIG. 4 is a perspective underside view of the tuning probe of FIG. 3;

FIG. 5 is a section along line VV of FIG. 3 showing the position of theprobe for tuning the center string of a three-string monotone stringgroup of a piano;

FIG. 6 is a section along line V-V of FIG. 3 showing the position of theprobe for tuning the right string of a three-string monotone stringgroup of a piano; and

FIG. 7 is a section along line VV of FIG. 3 showing the position of theprobe for tuning the left string of a three-string monotone string groupof a piano.

Basically, the invention uses a synchronous motor to drive a commutatorthrough a variable speed transmission at a plurality of preciselyselectable speeds. The commutator is arranged to close an electricalcircuit a pre determined number of times per revolution of thecommutator so as to energize and deenergize a solenoid connected inseries with the commutator and with a direct current power source at afrequency directly proportional to the rotational velocity of thecommutator. The solenoid is incorporated in a probe which can be placedover the strings of the instrument to be tuned in such a manner that thestring to be tuned is free to vibrate Within the magnetic field of thesolenoid. Preferably, the probe is supported by the adjacent string oneach side of the string to be tuned or by the sound box of theinstrument, as design considerations may require for any particularinstrument.

Referring now to the drawings, the numeral 10 in FIG. 1 denotes asynchronous motor of any well-known type whose'rotational velocity canbe very accurately maintained as a function of the sixty-cycleoscillations of the ordinary household current. The motor it) drives thecommutator 12 through a variable speed transmission 14 which may be ofany known type and which is adjustable, as by a handle 16, to twelvedifferent positions corresponding to the twelve notes of the chromaticscale. Indicating means such as 18 may be provided to indicate to theoperator to which note of the scale the transmission 14 is set.

A base speed adjustment or pitch control 19 is provided in thetransmission 14 to vary the basic pitch by any precise amount on eitherside of 440 cycles without changing the ratios of the various steps ofthe transmission. This is necessary for several reasons: either externaleffects may have changed the basic pitch of a piano as explainedhereinabove, or the tuner may wish to tune the instrument slightly sharpor slightly flat for artistic reasons, or the tuner may wish to spreadthe higher octaves and compress the lower octaves by predeterminedamounts, again for artistic reasons.

An illustrative embodiment of the commutator 12 is shown in FIG. 2. Thecommutator 12 may consist of an insulating disc 20 into which are set anouter cir- 3 cular row of contacts 22 and an inner circular row ofcontacts 24. All the contacts are electrically connected to the shaft 26as indicated at 28 and 33, respectively. Assuming that the commutatorturns in the direction of the arrow 32, the contacts 22 will be wiped bywiper 34, and the contacts 24 will be wiped by wiper 36. Wiper 3% is inconstant electrical contact with the shaft 26. The connections to wipers34, 36 and 38 are designated as a, b and respectively, whichdesignations correspend to similar notations on the diagram of FIG. 1.

Referring now back to FIG. 1, it will be seen that the wipers 34 and 38,together with the commutator 12, form part of an electrical circuitwhich includes the battery or other direct current source 4-0, a cable42, and a solenoid 44 located in the tuning probe 46 shown in FIGS. 3and 4, which in operation is placed adjacent the string 48 to be tuned.A switch 56 permits insertion of the wiper 36 into the electricalcircuit of the device for a purpose described in the Operation sectionhereof.

FIGS. 3 and 4 show a tuning probe adapted to be used in the device ofthis invention. The probe 46 includes a handle 52 which serves as aconduit for the cable 42, and a body 54 of nonmagnetic material,preferably plastic, in which the solenoid 44 is embedded. When the probe46 is placed over a string 48 (shown in phantom lines in FIGS. 3 and 4)which is to be tuned, the pole pieces 56, 58 of the solenoid 44 overliethe string 48 but do not touch it. The string 48 is received in thegroove 69 of the probe 46. Thus, the string 48 is free to vibrate whenthe probe 46 is placed onto the two adjacent strings d2, 64 (FIG. 4)which support it during the tuning operation. Mutes 66, 67 are providedto mute the strings 62, 64 while the string 48 is being tuned.

The manner in which the mutes 66, 67 can be used to mute all but thestring to be tuned in a monotone group of three piano strings d2, 48, 68is shown in FIGS. through 7. The figures depict the three positions ofthe probe 46 for tuning, respectively, string 48, string 68, and string62. 68 and 70 in these figures are the outside strings of the nextadjacent group of strings on each side of the group to be tuned. It willbe seen that in each position of the probe, two of the strings 62, 48,68 are wedged against the walls of the mutes 66 or 67, while the thirdone is free to vibrate in the groove 60.

If the instrument to be tuned is a piano, it is customary for thestrings 62, 48, 64 to be mounted on a metallic mounting strip whichelectrically connects all the strings together. In that case, the probe46 may be provided with contact fingers 72, 74 which are connected,respectively, to wires 76 and 78 in FIG. 3. It will be understood thatif this is done, the electrical circuit to the solenoid 44 is closedonly when the contact fingers 72, 74 are in contact with strings 62, 64and a continuous electrical path is established between the contactfingers 72, 74 through the string 62, the metallic mounting strip (notshown) and the string 64. The purpose of this arrangement is to savedirect current energy and prevent overheating of the probe, byenergizing the solenoid 44 only when the probe is actually in positionon the strings.

Operation The device of this invention operates on the principle that ifa resonant magnetizable body is subjected to a magnetic fieldoscillating at a frequency equal to its fundamental frequency, or to aharmonic or subharmonic thereof, the body will go into resonantoscillation at its fundamental frequency. For example, the middle Astring of a musical instrument has a fundamental frequency of 440 c.p.s.In order to cause a steel A string to resonate, it is thereforenecessary to subject it to a magnetic field oscillation at 44-0 c.p.s.or a multiple or submultiple thereof.

In any chromatic scale, if the fundamental frequency of a given note isk cycles per second, the fundamental frequency of the same note in thenext higher octave is exactly 2k cycles per second. Since resonantoscillations can be caused not only by excitation at the fundamentalfrequency, but also by excitation at a harmonic or subharmonicfrequency, magnetic oscillations of a frequency f=440 c.p.s. will causethe A string in any octave to resonate. Mathematically, therefore, apiano string will oscillate whenever its fundamental frequency satisfiesthe equation k=2 f, in which n is any integer. In the illustrativeembodiment shown in this application, magnetic oscillations at 440c.p.s. are produced by closing the electrical circuit of the solenoid 44four hundred and forty times per second by driving the commutator 12 ata speed such that wiper 34 rides over four hundred and forty contacts 22each second. For the other notes of the chromatic scale, the rotationalspeed of the commutator 12 would be proportionately less or more.

Specifically, if the synchronous motor 19 rotates at precisely 3600r.p.m., and if there are eight contacts 22 on the commutator 12, theratio of transmission 14 for the note A of the tempered chromatic scalemust be e0 8 r 440 l.0909

in which 1' is the transmission ratio expressed in motor revolutions percommutator revolution, represents the number of motor revolutions persecond, 8 is the number of contacts 22 on the commutator 12, and 440 isthe desired frequency in cycles per second.

For the various notes of the tempered chromatic scale, the frequenciesand transmission ratios are as shown in the following table:

Note Fundamental Transmission frequency ratio 493. 84 O. 9718 466. 16 1.0297 440. 00 1. 0909 415. 28 1. 1558 391. 92 1. 2247 369v 92 1. 2976349. 20 1. 3745 329. 60 1. 4553 311. 12 1. 5428 293. 6D 1. 6349 277.12 1. 7321 261. 60 1. 8348 Twelve transmission ratios are sufficient fortuning an entire piano because the fundamental frequency of any givennote is always twice the fundamental frequency of the same note in thenext lower octave. Therefore, since the string can be excited bymagnetic oscillations not only of its own fundamental frequency, butalso of any harmonics or subharmonics thereof, the entire tuning rangeof a piano can be covered by the twelve-step device described. However,in order to slightly increase the useful range of the tuner (the moreremote the exciting harmonic is from the fundamental, the lower theamplitude of the resonant oscillations will be), a second ring ofcontacts 24 may be provided on the commutator (FIG. 2) at angularpositions midway between the angular positions of the contacts 22. Asshown in FIG. 2, these contacts 24 are wiped by the wiper 36, and itwill be readily seen that if the wiper 36 is connected in parallel withwiper 34 by closing switch 59, the solenoid 46 will be excited atexactly twice the frequency it would be if the wiper 36 weredisconnected.

Inasmuch as the probe as is arranged to mute the strings adjacent to thestring being tuned, each string of a piano or other instrument can betuned individually, without interference from adjacent strings of amonotone group. The tuning operation is simple and is carried out asfollows: the basic pitch is first adjusted by properly setting the pitchcontrol 1%, whereupon the transmission M is set to the proper note ofthe scale by ad justing handle 16 until the indicator lid shows thedesired note. The probe is then placed over the string to be tuned, andthe tension of the string is adjusted until the string produces anaudible sound. The tension at which the string produces the maximumamplitude and clarity of sound is the correct adjustment. The adjustmentfor resonance is quite critical, and it is therefore very easy toquickly tune the string to the exact tension required.

It should be understood that although an illustrative embodiment of theinvention has been described herein to comply with the requirement ofthe patent statutes, ithe concept of this invention does not necessarilyrequire the exact physical structures described herein. Particularly,other types of electrical impulse generators or other types of magneticprobes than described herein may be used without departing from thespirit of the invention, as the requirements of any particular use maydictate. Consequently, I do not desire to be limited by the embodimentshown herein, but only by the scope of the following claims.

I claim:

1. A device for tuning musical instruments having a plurality ofparallel magnetizable electrically conductive electricallyinterconnected strings, comprising: means for selectively generatingelectrical impulses at predetermined frequencies; a solenoid connectedto said generating means; and probe means for holding said solenoid inspaced relationship to a string to be tuned while allowing said stringto vibrate freely, said probe means carrying a pair of contact barsinterposed in series in the electrical circuit connecting said solenoidand said generating means, said contact bars being arranged to closesaid electrical circuit through strings adjacent to the string beingtuned when said probe is in its proper operating position over thestring to be tuned.

2. A. tuning device for musical instruments having magnetizable strings,comprising: a motor; a commutator; means operatively connecting saidmotor and said commutator for selectively driving said commutator at aplurality of predetermined speeds; electrical contact means engagingsaid commutator to close an electrical circuit a predetermined number oftimes per revolution of said commutator, said electrical circuitincluding a source of ,rss ter direct current and a solenoid; and meansfor positioning said s lenoid in spaced relationship to a string to betuned while permitting said string to vibrate freely.

3. A device for tuning musical instruments having a plurality ofmagnetizable strings, comprising: a synchronous motor; a commutator; amulti-step transmission connecting said motor and said commutator toselectively rotate said commutator at a plurality of speeds havingpredetermined ratios, each speed being associated with a separate noteof a musical scale; means for collectively varying said speeds whilemaintaining their ratio; means to operate said transmission forstep-by-step selection of said speeds; first contact-and-Wiper meanscooperating with said commutator to close a first electrical circuit apredetermined number of times per revolution of said commutator; aportable probe; a source of direct current and a solenoid connected inseries with said first electrical circuit, said solenoid being containedin said probe; and means in said probe operative when said probe isplaced over a string to be tuned for holding said solenoid at apredetermined spacing from said string and allowing said string tovibrate freely while muting at least one string adjacent to it.

4. The device of claim 3, further comprising second contact-and-wipermeans cooperating with said commutator to close a second electricalcircuit midway between each closing or" said first electrical circuit;and switch means for selectively connecting said second electricalcircuit in parallel with said first electrical circuit.

5. A tuning device for musical instruments having magnetizable strings,comprising: means for selectively generating electrical impulses at aplurality of predetermined frequencies; a solenoid connected to saidgenerating means; and means for holding said solenoid in spacedrelationship to a string to be tuned While allowing said string tovibrate freely, said means including muting means for preventingvibration of strings next adjacent to said string to be tuned.

References tilted in the file of this patent UNlTED STATES PATENTS1,697,508 Kordick Jan. 1, 1929 1,908,258 Klopsteg May 9, 1933 2,514,315Dickerson July 4, 1950 2,779,920 Petrofr" Jan. 29, 1957

1. A DEVICE FOR TUNING MUSICAL INSTRUMENTS HAVING A PLURALITY OFPARALLEL MAGNETIZABLE ELECTRICALLY CONDUCTIVE ELECTRICALLYINTERCONNECTED STRINGS, COMPRISING: MEANS FOR SELECTIVELY GENERATINGELECTRICAL IMPULSES AT PREDETERMINED FREQUENCIES; A SOLENOID CONNECTEDTO SAID GENERATING MEANS; AND PROBE MEANS FOR HOLDING SAID SOLENOID INSPACED RELATIONSHIP TO A STRING TO BE TUNED WHILE ALLOWING SAID STRINGTO VIBRATE FREELY, SAID PROBE MEANS CARRYING A PAIR OF CONTACT BARSINTERPOSED IN SERIES IN THE ELECTRICAL CIRCUIT CONNECTING SAID SOLENOIDAND SAID GENERATING MEANS, SAID CONTACT BARS BEING ARRANGED TO CLOSESAID ELECTRICAL CIRCUIT THROUGH STRINGS ADJACENT TO THE STRING BEINGTUNED WHEN SAID PROBE IS IN ITS PROPER OPERATING POSITION OVER THESTRING TO BE TUNED.